Answer by Mohamed Mufeed for MariaDB SQL Query inner join table messages with table users

You should join the users table twice.

And I would go for LEFT JOIN rather than INNER JOIN as it is more appropriate.

SELECT     messages.id,    u1.username as name_from,    u2.username as name_to,    messages.contentFROM messages    LEFT JOIN users u1         ON messages.id_from = u1.id    LEFT JOIN users u2        ON messages.id_to = u2.id

The key here is that you join the tables with forign keys from messages table and their corresponding primary key from users table